Manufacture of dextrose controlling particle size



United States Patent Ofiice MANUFACTURE OF DEXTROSE CONTROLLING PARTICLE SIZE Robert G. Rohwer, John E. Cadotte, and Harold Reter, Clinton, Iowa, assignors, by mesne assignments, to Standard Brands Incorporated, New York, N.Y., a corporation of Delaware.

Application August 27, 1954, Serial No. 452,686 3 Claims. (Cl. 127--63) This invention relates, as indicated, to the manufacture of dextrose controlling particle size, and more parresidual mother liquor and is allowed to spin until there is essentially no further liquid removal.

Dextrose cake is plowed out of the centrifugal basket into some conveying means which takes it directly to the driers. The material entering the drier is almost without exception very lumpy, that is, having a good percentage of particles larger than U.S. No. 16 mesh, which is normally considered the largest size desirable for commerce. It also contains a large quantity of very fine loose crystals.

After drying the material is graded into the resulting granulations by variousmeans such as screening or air classification. The dry lumps are ground and returned to the dry streamfor grading.

This process has several-disadvantages. There is very little control over particle size, except by dry grinding, which will only produce smaller particles. Thus, there is no chance to increase the percentages of larger sized particles. Also, dry grinding produces dust. When dry dextrose is ground many crystal edges are apparently broken off and an undesirable amount of very fine material is produced. A certain amount of such material is carried along into the large particle sizes and creates an undesirable dust condition. Thirdly, lumps do not dry well due to their size and the inherent difliculty of removing moisture from lumps. In large lamps, some will be one and one-half inches to three inches in size,

there is a definite case hardening eflfect and the center of' the lump may actuallymelt due to the inability of the moisture to escape. customary procedure of drying is that particles made in this manner tend to fracture easily. It is, therefore, an object of this invention to increase the proportion .of larger sized particles in the manufacture of dextrose: p

It is a further object to reduce the dust usually associated with thelarger sized particles.

It is astill further object of the invention to produce harder and more durable particles,

It is a yetfurther object of the invention to iniprove drier efliciency.

Another object 'of thcinvention use afs ytstem that permits aconsiderable range ofcontrolover the size of the particles. x I A It-is still another objectof the invention to reduce the lump recycling load.

To the accomplishment of the foregoing and related ends said invention then comprises the features hereincertain illustrative embodiments of the invention, these A further disadvantage in the Patented Aug. 25, 1959 beingindicative, however, of but a few of the various ways in which the principle of the invention may be employed. i

Further objects and advantages of this invention will become evident as the description proceeds.

Broadly stated, this invention relates to the steps in the process for the manufacture of dextrose which comprises forming particles of the proper size prior to the drying operation.

In this specification and the examples which follow, materials which pass US. No. 16 mesh and are retained on U.S. No. 100 mesh screens are cited as examples of the particle sizes most desired. However, it is to be understood that particles of any desired size at least as large as those retained on U.S. No. 100 mesh screen may be produced.withoutdeparting from the scope of this invention.

' More particularly, this invention relates to the process for the manufacture of dextrose, which comprises centrifuging the magma to separatethe sugar and mother liquor, reducing the larger lumps of sugar and compacting finer particles into small agglomerates such as, for example, by milling to a size to pass an US. No. 16 mesh and will not pass an US. No. 100 mesh, and then drying such sugar. p V

In the drawing is shown a flow sheet of the process embodying the invention.

The liquor containing dextrose is prepared by the acid hydrolysis of starch. It is usual in the industry to crystallize in motion the dextrose-containing liquor, as is described inU.S. Patent No. 1,471,347, or one of the many variations, modifications, or improvements thereof.

. SEPARATION After crystallization, the resulting magma is subjected to a separation operation to remove the mother liquor (hydrol or first greens) from the dextrose hydrate, such as in centrifugal 1.

The remaining cake is washed with water to remove residual mother liquor, and then is allowed to spin until there is essentially no further liquid removal. Dextrose hydratecake remainingin thecentrifuge will be a rela tively hard-packed mass containing from about 12% to about 20% more usually from. 14% to 16%, moisture, including the 9.08% theoretical water of crystallization and about 5% to 7% or 10% of surface moisture. The process of this invention may be conducted at whatever maximum moisture content it is possible for the cake to contain without melting. The tendency is to centri fugeas much moisture from the cake as is possible. Centrifugal cake although compacted is quite soft and very friable as compared to the dry dextrose hydrate.

The centrifugal cake is plowed out of the centrifugal basket into some conveying means, such as a scroll conveyor 2, which takes it to the next operation.

The cake, leaving the centrifugal is very lumpy, that is, having a good percentage of particles larger than US. No. 16 mesh, normally, considered a larger size than desirable for commerce. It also contains a large quantity of very'fin e, loose crystals. This is what one would expectfrom a microscopic. examination of the crystal sizes in the crystallizer magmagoing'to the centrifuge which 'revealsthat the majority of crystals are smaller than U.S. mesh. H REDUCING AND COMPAQTING In, carrying. out. the. process of the Eijnvention it is necessary prior to drying, to formthe particles into the size ultimately desired in the final products- This step i ludes. trs tmsntqf the l d ed ss fii u alis e such asb rnillingextmsion, andthe liken- The centrifugal cake when it leaves the Eentrifilge is first milling. It analyzed:

not melt too much.

The heating of the cake might alternatively be accomplished by spraying steam either into the centrifugal basket or into the conveyor or by introducing, such as by spraying, onto the cake, a hot syrup of dextrose.

The upper limit of heating is determined by the point at which the sugar becomes too sticky to handle, usually between 145 F. to 150 F., at 15% moisture content. The usual temperature range is broadly from about 110 F. to about 150 F., preferably from about 125 F. to 145 F.

It should be understood that the process may be conducted without the heating step, but the increased temperature offers many unexpected advantages to the process if employed.

The centrifugal cake is then subjected to treatment which comprises forming at least 55% by weight, preferably at least 65% by weight, and most desirably at least 70% by Weight, of the undried centrifugal cake into particles of a size which will pass an U.S. No. 16 mesh, but will not pass an U.S. No. 100 mesh.

Any sizing device may be employed for this operation that will reduce the undried centrifugal cake to a size to pass an U.S. No. 16 mesh screen, and also compact the fine material into a larger size that will not pass through an U.S. No. 100 mesh, such as a mill, or an extrusion apparatus 3. Suitable devices include a sawtooth crusher or an extruding device which passes the material through apertures, for example, U.S. No. 16 or 20 mesh screen, which will produce particleswhich will pass an U.S. No. 16 mesh and be retained on U.S. No. 100 mesh screen.

DRYING The material is next fed to a drier 4, usually a hot air rotary type, and is ordinarily dried to approximately 8% moisture in the case of a dextrose hydrate, which is I trifuged to remove the mother liquor.

below theoretical moisture content of dextrose monohydrate, 9.08% by weight.

' After the drying operation, the material is graded in classifier 5 to various sizes by means such as screening or air classification, before the packaging operation 6.

Oversized particles which are separated in the classi- Example I The magma from the crystallizers was centrifuged.

The centrifugal cake was conveyed to thedrier without Percent by weight' Lumps:

On U.S. No. 16 mesh 33 Larger particles:

On U.S. No. 40 mesh 11 On U.S. No. 100 mesh 33 Smaller particles: V 1 7 'Thru U.S. No. 150 mesh -1 11 i The following specific examples are given to illustrate results which may be obtained in following the process and principles of this invention, but should not be construed as limiting the scope thereof, except as defined in the appended claims.

Example II The magma received from the crystallizers was centrifuged to remove the mother liquor. The undried centrifugal cake was then milled through a Mercer-Robinson type sawtooth crusherhaving onefeighth inch saws and one-fourth inch spacers. After being milled, the centrifugal cake was dried and analyzed:

Percent by weight Lumps:

On U.S. No. 16 mesh 25 Larger particles:

On U.S. No. 40 mesh 13 On US. No. mesh 42 Smaller particles:

On U.S. No. 150 mesh l2 Thru U.S. No. 150 mesh 8 Example III The magma received from the crystallizers was cen- The undried centrifugal cake was then extruded through an U.S. No. 16

' mesh screen andthen dried. The product analyzed:

' Percent by Weight On U.S. No. 16 mesh 0 Larger particles:

On U.S. No. 40 mesh 26 On U.S. No. 100 mesh 56 Smaller particles:

On U.S. No. 150 mesh 14 Thru U.S. No. 150 mesh 4 Example IV The magma received from the crystallizers was centrifuged. The undried centrifugal cake was then heated to F., and then milled through a Mercer-Robinson Example V The magma received from the crystallizers was centrifuged. The undried centrifugal cake was then heated to F., and then milled through a Mercer-Robinson sawtooth crusher. The product analyzed:

Percent by weight Lumps:

On U.S. No. 16 mesh 7 Larger particles: On U.S. No. 40 mesh 13 On U.S. No. 100 mesh 70 Smaller particles: i I

On U.S. No. mesh 0 Thru U.S. No. 150 mesh 1 Example VI The magma received from the crystallizers was centrifuged. The undried centrifugal cake was then heated to 135 F., then milled through a Mercer-Robinson sawtooth crusher. The product analyzed:

Percent by weight Example VII The magma received from the crystallizers was centrifuged. The undried centrifugal cake was then heated to 141 R, and then milled through a Mercer-Robinson sawtooth crusher. The product analyzed:

Percent by weight Lumps:

On U.S. No. 16 mesh 27 Larger particles:

On U.S. No. 40 mesh 54 On U.S. No. 100 mesh 18 Smaller particles:

On U.S. No. 150 mesh 1 Thru U.S. No. 150 mesh 0 One of the theories which has been developed to explain the unexpected control of particles size by the process of this invention is as follows. The larger particles are made up of agglomerates (conglomerates, mounted grain, married grain, rolled grain). The larger particles are greater than 100 mesh, while crystals in the magma are principally smaller than 100 mesh. To obtain larger particles, it is, therefore, necessary to form agglomerates. As there are fewer agglomerates in the magma, and as those that exist are small, these agglomerates are formed principally in the process after crystallization. It is believed that the application of heat dissolves a portion of the dextrose in the water which is present, making an adhesive syrup which tends to stick the fine particles together into agglomerates. Reducing the centrifugal cake to a smaller size, by extending it through a No. 16 mesh screen also compacts the smaller particles to larger sized agglomerates. The mill employed for reducing the size of the centrifugal cake has the same effect of forming agglomerates of the smaller sized particles.

In the drawing and specification, there have been set forth a preferred embodiment of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. The substitution of equivalents is contemplated, as circumstances may suggest or render expedient, without departing from the spirit or scope of this invention, as further defined in the following claims.

We claim:

1. In the process for the manufacture of dextrose wherein a liquor containing the dextrose is subjected to a crystallization operation followed by the removal of the mother liquor resulting in the formation of a sugar cake, the steps which comprise: forming a mixture'of sugar cake of dextrose with a small amount of adhesive syrup of dextrose by heating said sugar cake to a temperature in the range from about 110 F. to 150 F. and for a period short of substantial melting, said sugar cake of dextrose having lumpy particles and a large quantity of fine loose particles at a moisture content of about 12% to about 20% by weight, said adhesive syrup being formed in amounts at least sufiicient to compact said fine loose particles but not in amounts suflicient to make said mixture too sticky for handling; reducing and compacting suflicient proportions of said lumpy and fine particles of said sugar cake into particles of sizes such that when dried at least 55 percent by weight will be retained on U.S. mesh screen and will pass a U.S. No. 16 mesh screen; and then drying said particles to a moisture content below 9.08% by weight.

2. In the process for the-manufacture of dextrose wherein a liquor containing the dextrose is subjected to a crystallization operation followed by the removal of the mother liquor resulting in the formation of a sugar cake,

the steps which comprise: forming a mixture of sugar,

cake of dextrose by heating to a temperature in the range from about F. to F. and for a period short of substantial melting With a small amount of adhesive syrup of dextrose by admixing steam with said sugar cake, said sugar cake of dextrose having lumpy particles and a large quantity of fine loose particles, said adhesive syrup being formed in amounts at least sufiicient to compact said fine loose particles but not in amounts suflicient to make said mixture too sticky for handling; reducing and compacting sufiicient proportions of said lumpy and fine particles of said sugar cake into particles of sizes such that when dried, at least 55 percent by weight will be retained on U.S. 100 mesh screen and will pass a U.S. No. 16 mesh screen; and then drying said particles to a moisture content below 9.08% by Weight.

3. In the process for the manufacture of dextrose wherein a liquor containing the dextrose is subject to a crystallization operation followed by the removal of the mother liquor resulting in the formation of a sugar cake, the steps which comprise: heating the sugar cake of dextrose having lumpy particles and a large quantity of loose fine particles at a moisture content of about 12% to about 20% by weight to a temperature within the range from about 110 F. to about 150 F. and for a period short of substantial melting; reducing and cornpacting suflicient proportions of said lumpy and loose fine particles into particles of sizes such that When dried at least 55 percent by weight Will be retained on U.S. 100 mesh screen; and then drying said particles to a moisture content below 9.08% :by Weight.

References Cited in the file of this patent UNITED STATES PATENTS 401,363 Moresi Apr. 16, 1889 541,010 Reid Tune 11, 1895 552,422 Cook Dec. 31, 1895 1,826,701 Ames Oct. 13, 1931 2,033,416 Daley Mar. 10, 1936 2,098,604 Whymper Nov. 9, 1937 2,205,177 Schlegel June 18, 1940 2,299,288 Whymper Oct. 20, 1942 2,400,292 Dalton May 14, 1946 UNITED STATES PATENT OFFICE CERTIFIQATE OF CORRECTION Patent No. 2,901,382 August 25, 1959 Robert G. Rohwer et a1.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should readas corrected below.

Column 5, lines 43 and 44, for "extending" read extruding -r,

Signed and sealed this 8th day of March 1960 (SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents 

1. IN THE PROCESS FOR THE MANUFACTURE OF DEXTROSE WHEREIN A LIQUOR CONTAINING THE DEXTROSE IS SUBJECTED TO A CRYSTALLIZATION OPERATION FOLLOWED BY THE REMOVAL OF THE MOTHER LIQUOR RESULTING IN THE FORMATION OF A SUGAR CAKE, THE STEPS WHICH COMPRISE FORMING A MIXTURE OF SUGAR CAKE OF DEXTROSE WITH A SMALL AMOUNT OF ADHESIVE SYRUP OF DEXTROSE BY HEATING SAID SUGAR CAKE TO A TEMPERATURE IN THE TRANGE FROM ABOUT 110*F. TO 150*F. AND FOR A PERIOD SHORT OF SUBSTANTIAL MELTING SAID SUGAR CAKE OF DEXTROSE HAVING LUMPY PARTICLES AND A LARGE QUANTITY OF FINE LOOSE PARTICLES AT A MOISTURE CONTENT OF ABOUT 12% TO ABOUT 20% BY WEIGHT, SAID ADHESIVE SYRUP BEING FORMED IN AMOUNTS AT LEAST SUFFICIENT TO COMPACT SAID FINE LOOSE PARTICLES BUT NOT IN AMOUNTS SUFFICIENT TO MAKE SAID MIXTURE TOO STICKY FOR HANDLING REDUCING AND COMPACTING SUFFICIENT PROPORTIONS OF SAID LUMPY AND FINE PARTICLES OF SAID SUGAR CAKE INTO PARTICLES OF SIZES SUCH THAT WHEN DRIED AT LEAST 55 PERCENT BY WEIGHT WILL BE RETAINED WHEN DRIED AT LEAST 55 PERCENT BY WEIGHT WILL BE RETAINED ON U.S. 100 MESH SCREEN AND WILL PASS A U.S. NO 16 MESH SCREEN, AND THEN DRYING SAID PARTICLES TO A MOISTURE CONTENT BELOW 9.08% BY WEIGHT. 